Alan Conolly said his client, Leonard John Warwick, had been a successful litigant and had not had the skills time or motivation to commit the crimes.

"The idea he could have, by himself, constructed a bomb is absurd," he said on Monday in the defence opening at Warwick's judge-alone trial in the NSW Supreme Court.

"And the evidence he might have the expertise comes out of Monty Python - it is absurd and ridiculous."

The 71-year-old has pleaded not guilty to four murders - including the shooting deaths of his brother-in-law and a judge - and 20 other offences relating to seven events that occurred between February 1980 and July 1985.

The prosecutor previously said Warwick was involved in a long-running Family Court dispute which "inextricably linked" him to the seven events and provided him with the motivation the Crown said existed for him to commit the offences.

They included the 1980 shooting murders of his brother-in-law Stephen Blanchard and Justice David Opas; the bombing of Justice Richard Gee's home and of the Family Court building in Parramatta in 1984; and, in the same year, the bombing of the home of Justice Ray Watson in which his wife Pearl was killed.

Warwick in 1985 allegedly set off a bomb that ripped apart a Jehovah's Witnesses hall, killing Graham Wyke and injuring 13 people.

The organisation had given support to his ex-wife Andrea Blanchard.

Mr Conolly on Monday rejected an argument that the case involved "tendency and coincidence" evidence against his client.

"The events are unconnected as far as Mr Warwick is concerned," he said.

The case involved an unjust and unfair focus on Warwick, as well as "improper behaviour of certain policemen".

Referring to possible perpetrators, Mr Conolly said: "During this trial, those people will be named".

Some had made "outrageous public statements" about the Family Court system and some of its judges.

Some had access to skills and networks needed to carry out the bombings, he said.

Referring to the murder of Warwick's brother-in-law, the lawyer said the defence had evidence he dealt in drugs and was mentally unstable and unwell.

Meanwhile, Warwick had a "benign" relationship with him.

Retired Family Court judge Josephine Maxwell said after the deaths of Justice Opas and Pearl Watson, the media reported a man - not Warwick - who was publicly saying she and two other judges "were said to be next in line".

She also remembered police telling her about a threat which said "I'd be dead by midnight".

The trial is continuing before Justice Peter Garling.

Australian Associated Press